If the schools have photoshop, then we can analyze gel images.
On something like this, but in blue:
At the top there is a line of wells going horizontally. The DNA bands are shown in vertical columns. We can enhance the image to bring out the bands through brightness/contrast or adjusting curves. Then we measure the distance between the line of wells at the top and the DNA bands below. In this gel image, the furthest column to the right is a set of standard bands of known size to which the other DNA bands can be compared graphically.
On something like this, but in blue:
At the top there is a line of wells going horizontally. The DNA bands are shown in vertical columns. We can enhance the image to bring out the bands through brightness/contrast or adjusting curves. Then we measure the distance between the line of wells at the top and the DNA bands below. In this gel image, the furthest column to the right is a set of standard bands of known size to which the other DNA bands can be compared graphically.